Causality and Noumenon

The most important distinction in Kant's system is that between Phenomenon and Noumenon, the most important thesis regarding which is that the latter has causal efficacy with respect to the former, but not vice versa.  On that basis, he posits that Reason is a Noumenal Cause, thereby immunizing it from both of Hume's main theses--by arguing that the concept of Causality as a Constant Conjunction, and that of Reason as the slave of Passion, each applies only to Phenomena.  Accordingly, the Noumenon-Phenomenon distinction could be taken to signify a new era in Human history--that of a causal efficacy with respect to its Environment that is not a mere reaction to it, i. e. a transition to Adaptation-Of as its primary of interaction with its Environment. However, there is a more traditional ground to that distinction.  The repudiation of Geocentrism creates a Theological crisis--by displacing the deity from physical contiguity with the Human world, the concept of divine causal efficacy becomes groundless, and, hence, problematic for a doctrine such as Theism, according to which divine intervention in Human affairs is always possible, though not necessarily always actual.  So, the Phenomenon-Noumenon distinction provides a home for that deity, and a new ground for its causal efficacy.  Now, much of Kant's trilogy seems to express the more secular of the two orientations, perhaps one that foreshadows an Ecological concept of Human history.  But, the dedication of the final sections of the Critique trilogy to a restoration of the the existence and power of a deity, i. e. at the very end of a discussion of Teleology in the Third Critique,  is indicative of what Kant's ultimate priority is.